The present invention relates to an electromagnetic fuel injector, particularly for supplying a motor vehicle internal combustion engine, and which provides for eliminating or reducing magnetic leakage towards the injection nozzle.
Electromagnetic fuel injectors are known to comprise a casing, usually made of steel or ferromagnetic material, with a projecting injection nozzle and housing a plunger for opening or closing the nozzle, an anchor integral with the plunger, and a core with an electric winding designed, when the winding is supplied with current, to attract the anchor and so operate the plunger for opening the nozzle for the required fuel injection time.
A major drawback of known injectors of the aforementioned type, especially those with anchors designed for radial closure of the electromagnetic flux, is that they are subject to a certain amount of leakage of the magnetic flux produced by the electromagnet, i.e. core and winding, controlling the plunger. Certain lines of force, in fact, may be closed across the casing and even along this casing and across the nozzle. As, for reasons of mechanical strength, both the nozzle and plunger are usually formed of ferromagnetic material, the electromagnetic attraction produced by such leakage results in the plunger sticking to the sealing seat on the nozzle, thus resulting in delayed opening of the nozzle, injection of less than the required amoung of fuel, and impaired performance of the injector as a whole.